Titanium-doped Indium Oxide Research Articles

Sub-volt high-speed silicon MOSCAP microring modulator driven by high-mobility conductive oxide

Silicon microring modulator plays a critical role in energy-efficient optical interconnect and optical computing owing to its ultra-compact footprint and capability for on-chip wavelength-division multiplexing. However, existing silicon microring modulators usually require more than 2 V of driving voltage (Vpp), which is limited by both material properties and device structures. Here, we present a metal-oxide-semiconductor capacitor microring modulator through heterogeneous integration between silicon photonics and titanium-doped indium oxide, which is a high-mobility transparent conductive oxide (TCO) with a strong plasma dispersion effect. The device is co-fabricated by Intel’s photonics fab and our in-house TCO patterning processes, which exhibits a high modulation efficiency of 117 pm/V and consequently can be driven by a very low Vpp of 0.8 V. At a 11 GHz modulation bandwidth where the modulator is limited by the RC bandwidth, we obtained 25 Gb/s clear eye diagrams with energy efficiency of 53 fJ/bit.

Reliability of transparent conductive oxide in ambient acid and implications for silicon solar cells

Transparent conductive oxide (TCO) films, known for their role as carrier transport layers in solar cells, can be adversely affected by hydrolysis products from encapsulants. In this study, we explored the morphology, optical-electrical properties, and deterioration mechanisms of In2O3-based TCO films under acetic acid stress. A reduction in film thickness and carrier concentration due to acid-induced corrosion was observed. X-ray photoelectron spectroscopy and inductively coupled plasma emission spectrometry analyses revealed that TCOs doped with less-reactive metals exhibited enhanced corrosion resistance. The efficiency of silicon heterojunction (SHJ) solar cells with tin-doped indium oxide, titanium-doped indium oxide, and zinc-doped indium oxide films decreased by 10%, 26%, and 100%, respectively, after 200 ​h of corrosion. We also found that tungsten-doped indium oxide could effectively safeguard SHJ solar cells against acetic acid corrosion, which offers a potential option for achieving long-term stability and lower levelized cost of solar cell systems. This research provides essential insights into selecting TCO films for solar cells and highlights the implications of ethylene-vinyl acetate hydrolysis for photovoltaic modules.

On-chip wavelength division multiplexing filters using extremely efficient gate-driven silicon microring resonator array

Silicon microring resonators (Si-MRRs) play essential roles in on-chip wavelength division multiplexing (WDM) systems due to their ultra-compact size and low energy consumption. However, the resonant wavelength of Si-MRRs is very sensitive to temperature fluctuations and fabrication process variation. Typically, each Si-MRR in the WDM system requires precise wavelength control by free carrier injection using PIN diodes or thermal heaters that consume high power. This work experimentally demonstrates gate-tuning on-chip WDM filters for the first time with large wavelength coverage for the entire channel spacing using a Si-MRR array driven by high mobility titanium-doped indium oxide (ITiO) gates. The integrated Si-MRRs achieve unprecedented wavelength tunability up to 589 pm/V, or VπL of 0.050 V cm with a high-quality factor of 5200. The on-chip WDM filters, which consist of four cascaded ITiO-driven Si-MRRs, can be continuously tuned across the 1543–1548 nm wavelength range by gate biases with near-zero power consumption.

Modulation of the TCO/MoOx Front Contact Enables >21% High-Efficiency Dopant-Free Silicon Solar Cells

Highly efficient dopant-free silicon solar cell requires effective electron- and hole-selective contacts. We have recently reported a remarkable efficiency of 21.3% for dopant-free silicon solar cells with a low work function and transparent and conductive MgFxOy electron extraction. The transparent conductive oxide (TCO) films and molybdenum oxide (MoOx) front hole contact also play significant roles in the high efficiency of dopant-free solar cells. In this study, zinc-doped indium oxide (IZO), tin-doped indium oxide (ITO), and titanium-doped indium oxide (ITiO) have been deposited via magnetron sputtering at room temperature. The work function and optoelectrical properties of TCO films and energy band bending together with the MoOx layer are investigated. The impact of this band bending on the photoelectrical performances of devices is analyzed in detail as a function of the MoOx/TCO work function mismatch. The optimized IZO film presents the highest work function (5.21 eV) and conductivity (2140 S/cm), resulting in reduced barrier height at the MoOx/TCO interface and enhanced hole-selective transport. The light-soaking treatment is introduced to repair the sputtered damage during the IZO deposition. Finally, an impressive cell efficiency of 21.0%, together with Voc, FF, and Jsc of 712.4 mV, 76.4%, and 38.6 mA/cm2, respectively, shows great potential and provides an effective solution to obtain highly efficient dopant-free silicon solar cells.

Effect of cesium fluoride treatment in bifacial Cu(In1-x,Gax)Se2 solar cell

Bifacial Cu(In1-x,Gax)Se2 (CIGS) thin film solar cells were fabricated on titanium-doped indium oxide (ITiO) coated soda-lime glass substrate, and the effect of cesium fluoride (CsF) treatment on solar cell performance was investigated. CsF treatment improved the photovoltaic properties of CIGS/ITiO-based solar cells not only under front-side illumination but also under rear-side illumination. The quantum efficiency for rear-side illumination improved significantly in CsF-treated CIGS solar cells. As a result, the bifaciality improved in the CsF-treated CIGS solar cell. ITiO exhibited good contact with the CIGS thin film, regardless of Cs incorporation. In addition, the effect of heat-light soaking treatment was also investigated in CIGS/ITiO-based solar cells.

Characterization of field-effect mobility at optical frequency by microring resonators

A novel characterization method is proposed to extract the optical frequency field-effect mobility ( μ op , FE ) of transparent conductive oxide (TCO) materials by a tunable silicon microring resonator with a heterogeneously integrated titanium-doped indium oxide ( ITiO ) / SiO 2 / silicon metal–oxide–semiconductor (MOS) capacitor. By operating the microring in the accumulation mode, the quality factor and resonance wavelength shift are measured and subsequently used to derive the μ op , FE in the ultra-thin accumulation layer. Experimental results demonstrate that the μ op , FE of ITiO increases from 25.3 to 38.4 cm 2 ⋅ V − 1 ⋅ s − 1 with increasing gate voltages, which shows a similar trend as that at the electric frequency.

Performance Analysis of Ti-Doped In2O3 Thin Films Prepared by Various Doping Concentrations Using RF Magnetron Sputtering for Light-Emitting Device

The influences of doping amounts of TiO2 on the structure and electrical properties of In2O3 films were experimentally studied. In this study, titanium-doped indium oxide (ITiO) conductions were deposited on glass substrate by the dual-target-type radio frequency magnetron sputtering (RFS) system under different conditions of Ti-doped In2O3 targets, from Ti-0.5 wt% to Ti-5.0 wt%, along with 10 mTorr and 300 W pressure of RF power control that was used as a cost-effective transparent electrochemiluminescence (ECL) cell. From this process, the correlation between structural, optical, and electrical properties is reported. It was found that the best 1.14×10−4 Ω cm of resistivity was from Ti-2.5 wt% with the highest carrier concentration (1.15 × 1021 cm-3), Hall mobility (46.03 cm2/V·s), relatively transmittance (82%), and ECL efficiency (0.43 lm·W-1) with well crystalline structured and smooth morphology. As a result, researchers can be responsible for preparing ITiO thin films with significantly improved microstructure and light intensity performance for the effectiveness of the display devices, as well as its simple process and high performance.

Analysis and optimisation of the glass/TCO/MZO stack for thin film CdTe solar cells

Magnesium-doped Zinc Oxide (MZO) films have recently been proposed as a transparent buffer layer for thin film CdTe solar cells. In this study, the band gap of MZO buffer layers was tuned for CdTe solar cells by increasing the substrate temperature during deposition. Films were deposited by radio-frequency magnetron sputtering. Devices incorporating an optimised MZO buffer layer deposited at 300 °C with a band gap of 3.70 eV yielded a mean efficiency of 12.5% and a highest efficiency of 13.3%. Transmission electron microscopy showed that MZO films are uniformly deposited on the transparent conductive oxide (TCO) layer surface. The favourable band alignment seems to positively counterbalance the low doping level of the MZO layer and its high lattice mismatch with CdTe. Titanium-doped indium oxide, tin-doped indium oxide and aluminium-doped zinc oxide TCOs were also used as alternatives to fluorine-doped tin oxide (FTO), in combination with MZO films. The use of titanium-doped indium oxide and tin-doped indium oxide TCOs did not improve the device efficiency achieved compared with FTO, however using aluminium-doped zinc oxide coupled with a boro-aluminosilicate glass substrate the mean and highest efficiencies were further improved to 12.6% and 13.4% respectively.

A balancing between super transparency and conductivity of solution combustion derived titanium doped indium oxide: Effect of charge carrier density and mobility

In this contribution, super transparent (~100%) and conducting In14Ti1O23 (Titanium doped Indium oxide; InTiO) films were reported via solution combustion processing with acetylacetone as fuel. Both bulk-powder and thin film systems were studied and revealed the efficacy of low temperature combustion synthesis which yielded crystalline InTiO powder at 150 °C and its film counterpart had shown pronounced crystalinity with temperature. Also, all films with varying annealing temperature were smooth with rms value ranging from 0.29 nm to 1.9 nm. In addition, the charge carrier density in all films found to be of the order 1019 cm−3, possessing highest transparency nearly equals to uncoated glass at an annealing temperature of 350 °C having maximum of ~67% metal-oxygen-metal framework (or lattice oxygen) confirmed via X-ray photoelectron spectroscopy. Also, the highest conductivity of 20 S/cm at an annealing temperature of 450 °C clearly conveyed the potential of solution combustion processing in the fabrication of ultra-transparent InTiO films with no sophistication in the film fabrication.

Influence of Substrate Temperature and Radio Frequency Power to TiO2 on Electrical, Optical and Structure Properties of Titanium Doped Indium Oxide

Influence of Substrate Temperature and Radio Frequency Power to TiO₂ on Electrical, Optical and Structure Properties of Titanium Doped Indium Oxide

Optimization of titanium-doped indium oxide anodes for heterojunction organic solar cells

Optimization of titanium-doped indium oxide anodes for heterojunction organic solar cells

Effects of H2 plasma treatment on the electrical properties of titanium-doped indium oxide films prepared by polymer-assisted deposition

The effects of hydrogen (H2) plasma on the optical and electrical properties of titanium-doped InO (TIO) grown on glass substrates using polymer-assisted deposition are reported. Samples were exposed to H2 plasma formed by inductively coupled plasma (ICP). After plasma treatment at a power of 100 W, the sheet resistance of the TIO films decreased from 11 000 to 285 Ω/sq. Additionally, the Hall mobility and sheet carrier concentration of the films increased as the ICP source power was increased to 100 W, without affecting the optical transmittance of the films, due to the removal of the polymer residues and the formation of oxygen vacancies.

Analysis of Titanium-Doped Indium Oxide Based Optically Transparent Patch Antenna for Terahertz Communications

Analysis of Titanium-Doped Indium Oxide Based Optically Transparent Patch Antenna for Terahertz Communications

Effects of Titanium Doping Concentration on the Structural and Electrical Properties of Sputtered Indium Oxide Films.

The surface structure and electrical properties of titanium-doped indium oxide (ITiO) films prepared by RF magnetron sputtering were investigated. The doping concentration of TiO2 in the In2O3 target was changed from 1.0 wt.% to 10.0 wt.% with increments of 1.0 wt.%. At a Ti content of 5.0 wt.%, the optimum growth conditions were achieved. The finest value of hall mobility, carrier concentration, and resistivity of the deposited film reached 47.03 cm2Ns, 1.148 x 10(21) cm-3 and 1.14 x 10(-4) Ωcm, respectively. Then the transmittance was achieved up to 82% at 570 nm. The peaks of the XRD spectra became more intense and sharp as the Ti concentration increased up to 2.5 wt.% but a higher Ti content of 10.0 wt.% retarded a growth of In2O3 grains. The surface roughness of the films by examination of surface morphology using AFM also rose with increase of Ti doping concentration.

High Mobility Titanium-doped Indium Oxide for Use in Tandem Solar Cells Deposited via Pulsed DC Magnetron Sputtering

The effects of pulsed DC (PDC) magnetron sputtering on the crystalline structure of the high mobility transparent conducting oxide (TCO), titanium-doped indium oxide (ITiO), are investigated. High mobility (μ >100 V-1s-1cm2) ITiO films are deposited by PDC magnetron sputtering and compared to RF deposited films using optimized conditions. These high mobility ITiO films have shown to extend the transmission in the NIR region compared to typical TCOs, such as ITO, exhibiting their potential in a tandem or multiple junction solar cell application. ITiO films deposited by PDC magnetron sputtering offer an increased deposition rate without a significant reduction in mobility when compared to RF sputtering, thus potentially offering PDC as a preferred industrial choice over RF sputtering. Structural characterization of the ITiO films prepared by PDC show a change in crystalline orientation and crystallite shape when compared to RF films, measured by XRD and SEM, which have been linked with the electrical parameters of the TCO.

Structural and electrical properties of sputtering power and gas pressure on Ti-dope In2O3 transparent conductive films by RF magnetron sputtering

Transparent conductive titanium-doped indium oxide (ITiO) films were deposited on Corning glass substrates by RF magnetron sputtering method. The effects of RF sputtering power and Ar gas pressure on the structural and electrical properties of the films were investigated experimentally, using a 2.5wt% TiO2-doped In2O3 target. The deposition rate was in the range of around 20–60nm/min under the experimental conditions of 5–20mTorr of gas pressure and 220–350W of RF power. The lowest resistivity of 1.2×10−4Ωcm, the average optical transmittance of 75%, the high hall mobility of 47.03cm2/Vs and the relatively low carrier concentration of 1.15E+21cm−3 were obtained for the ITiO film, prepared at RF power of 300W and Ar gas pressure of 15mTorr. This resistivity of 1.2×10−4Ωcm is low enough as a transparent conducting layer in various electro-optical devices and it is comparable with that of ITO or ZnO:Al conducting layer.

Structural and Electrical Properties of Titanium-Doped Indium Oxide Films Deposited by RF Sputtering

Titanium-doped indium oxide (ITiO) is a high-quality transparent conducting oxide commonly used as the contact for photovoltaic. The transparent conductive titanium-doped indium oxide (ITiO) films were deposited on Corning glass substrates by RF magnetron sputtering method. The effects of RF sputtering power and Ar gas pressure on the structural and electrical properties of the films were investigated experimentally, using a 2.5 wt% TiO2 -doped In2O3 target. The deposition rate was in the range of around 20 to 60nm/min under the experimental conditions of the gas pressure and the RF Magnetron sputtering power. In this case, the lowest resistivity of 1.2×10-4-cm and the average optical transmittance of 75% were obtained for the ITiO film, prepared at RF power of 300W and Ar gas pressure of 15 mTorr. This resistivity of 1.2×10-4-cm is low enough as a transparent conducting layer in various electro-optical devices and it is comparable with that of ITO or ZnO:Al conducting layer.

Preparation of Titanium-doped Indium Oxide Films by Ultrasonic Spray Pyrolysis Method

Titanium-doped indium oxide (ITiO) films were deposited on soda-lime glass by ultrasonic spray pyrolysis. The optimum conditions of deposition parameters, such as dopant concentration for lowest resistivity were investigated. Phase formation and microstructure of the films were examined by XRD and SEM. AFM was used to obtain the surface topology of the prepared films. The optical transmission and resistivity of films were determined by UV-Vis-NIR spectrophotometer and Van der Pauw method respectively. The resistivity of films depended on the titanium content. The feasibility study of using the ITiO as one of the TCO for solar cell was discussed.

High mobility and visible–near infrared transparent titanium doped indium oxide thin films produced by spray pyrolysis

This paper deals with high transparent and high conductive oxides based on polycrystalline titanium (Ti) doped (0.5–3at.%) indium oxide (IO) thin films produced on glass substrates at 400°C by spray pyrolysis technique. X-ray diffraction analysis confirmed the cubic bixbyite structure of indium oxide. A high mobility of ~97cm2V−1s−1, a carrier concentration of ~1.55×1020cm−3 and a resistivity of ~4.11×10−4Ω-cm with ~83% of transmittance in the wavelength ranging between 400 and 2500nm were obtained for 2at.% Ti doping films, rivalling so to the best known transparent conducting oxide based on indium tin oxide. Moreover, the transmittance in the broad wavelength ranging between 400 and 2500nm is over 83%, leading so to an increasing carrier generation towards the near infrared region of the spectrum, as required for applications such as solar cells. We also notice that increasing the doping concentration widened the optical band gap and caused a small Burstein–Moss shift, due to mobility decrease, as expected.

Fundamental Properties of Titanium-Doped Indium Oxide and Its Application to Thin-Film Silicon Solar Cells

We have investigated the fundamental optoelectronic properties of newly developed transparent conductive oxide (TCO) materials, e.g., titanium-doped indium oxide (InTiO). InTiO films, being deposited at 50 °C by the RF-magnetron-sputtering method followed by thermal annealing at 200 °C, show excellent optoelectronic properties for solar-cell application. We have demonstrated the improved photovoltaic performance of n–i–p microcrystalline-silicon (µc-Si:H) solar cells whose i layer is prepared at a high rate of 2.3 nm/s using a stacked structure of InTiO with aluminum-doped zinc oxide (AZO) as top (front) TCO layers.